Frames / Images Per Second
Let’s give you a quick lesson in translation and calculation of video “speed” or “frame rates.”
Some manufacturers use different expressions when identifying the speed capabilities of their product. It will become increasingly apparent why this is misleading.
- Thirty (30) “frames-per-second”(abbreviated as “fps”) is “real-time,” ”real-motion” video in the NTSC (North America) video standard.
- Twenty-five (25) “frames-per-second”(abbreviated as “fps”) is “real-time,” ”real-motion” video in the PAL (International) standard.
This is not to be confused with “fields-per-second” (also abbreviated as “fps”). Unfortunately, two (2) fields equal one (1) frame. So when a manufacturer states “30 fps” on their literature are they talking fields or frames? Are they talking about each channel of video or total capacity of the system? Are they talking about the system limitation or the operating capability?
When comparing a DVR’s fields (FPS), images (IPS) or frames-per-second (FPS); display, recording or playback performance claims; be careful to take into consideration all the factors that will apply to your particular application. Once again, manufacturers’ claims may be based on “optimal” conditions and have little to do with reality and what you are trying to achieve. So always check to see if the total number of FPS/FPS/IPS quoted is for the entire DVR capture card or is it on a per channel basis. Is it for display and record? You simply have to test it anyway, as claims are just that; claims. Besides if you don’t the regulators will
It’s kind of like the MPG sticker on a new car. Do you know anyone that ever got that kind of mileage? Not unless they were going downhill, in neutral, with a strong tail-wind!
Remember also what you are viewing live has nothing to do with the recorded quality, they are separate and distinct. So watching a live picture has little value, although if the live video is poor you are already in trouble.